I'm in a 1st floor 2 bedroom apartment now, and have found that central air set at 77 provides a comfortable environment in the living kitchen, dining and 2nd bedroom.

Unfortunately, my master bedroom is noticeably warmer, regardless, meaning turning the unit down to 74ish. I have a daughter with really bad alergies, so warm means runny nose, less sleep, etc. I'm currently use fans at the master br door to circulate air from main portion of apt into that room, and an old shop trick with a quality 3m 20x20 filter strapped to a box fan to ensure apartment air is constantly filtered. This renders the box fan very inefficient, but does help constantly filter dust, dander, etc., and rotate it in the direction we are in. I'll be here a while, since my wife has decided to divorce me, so I'm trying to make sure I have the best return on my investment, while cutting cost as significantly as possible. LCD TV and a laptop in the master that generate heat, but even with these devices off, it's so warm in the master bedroom. I'm trying to find the best place to spend my money. I thought I'd start with programmable thermostat and maybe even putting the fans on timers.

would a window unit or portable a/c unit be a viable option, or would it take too long to recoup the investment?

Thanks, Scott